Conventionally, contents data such as audio data, image data, video data and computer programs are generally delivered in the form of package media that are independent recording media such as optical discs containing the data. Contents data are also electronically delivered by way of telecommunication networks such as Internet on a pay per delivery basis.
Contents data are delivered more advantageously by electronic delivery means than by package media because the former does not involve any transfer of package media that are physical objects and contents data can be directly transferred from a computer to another computer. Thus, electronic delivery means is highly effective for broad distribution of contents data. On the other band, people have the desire of possessing objects and hence may not be able to satisfy the desire unless they posses the package media they want.